Sean Plott tends to stay at home most days. But when he emerges from his Los Angeles house, he’s a star.

“Pretty much every time I go out somewhere, I get recognized at least once,” he says. Though he says he appreciates his fans, he wishes they wouldn’t treat him as a larger-than-life figure. After all, he’s just some guy.

This familiar complaint usually comes from actors bemoaning paparazzi. But Plott, more or less, is a professional geek. Under the handle Day[9], he hosts a web show that attracts up to 15,000 viewers a night. He has 114,000 followers on Twitter and nearly 50 million views on his YouTube channel. His fame revolves around the world of competitive video gaming, a field that’s been thriving internationally for a decade and is reaching critical mass in the U.S.

For the uninitiated: Yes, people play video games for a living. eSports is a thriving business — and even a government-supported one in South Korea, where players are rock stars who earn well over six figures thanks to endorsement deals. (TIME stopped by a team house, where players eat, sleep and breathe gaming, in 2007.) Gaming hasn’t hit that level yet in the States. But since the release of StarCraft II in 2010, American companies like Major League Gaming, which stages tournaments, and Twitch, which streams games and shows about gaming online, have seen business grow in leaps and bounds.

This weekend in Anaheim, Calif., Major League Gaming expects to break every viewing record they’ve ever set. Several tournaments will go on at once — one in StarCraft II, one in League of Legends and one in fighting games Mortal Kombat, Soul Calibur V and King of Fighters XIII. Several top Korean players will be playing an expo match as well. But arguably the biggest draw is Blizzard’s demo preview of the StarCraft II expansion Heart of the Swarm. These blockbuster events, plus their convenient timing after E3, mean that MLG is expecting close to 20,000 spectators. Far more than that will watch online.

As of now, StarCraft II is the king of eSports. Ask most players to describe the game to a “noob” and they’ll inevitably compare it to chess. Each race — the human Terran, the advanced alien Protoss and the insect-like Zerg — has its own separate units but, as a whole, is equally powerful.

This balance means winning is more about strategy, ingenuity in the heat of battle and quick reaction times (recorded in APM, or actions per minute) than logging in long hours leveling up your character. Viewers are primed to understand the tournament-style of eSports because they experience it every time they play ranked matches online.

“I think that StarCraft is really the only game designed from the ground up to be an eSport,” says Mike Morhaime, CEO of Blizzard. “As a spectator, the whole asymmetry of information — meaning you can see things that the players don’t know — makes it fun to watch.”

Blizzard says it has sold more than 5 million copies of the game in 11 different languages. But that doesn’t make it invulnerable to young challengers like League of Legends, the free-to-play fantasy game that pits teams of “Champions” against each other in volatile, magic-filled battles that satisfy two key elements of a good eSports game: it’s fun to watch and easy to understand.

In South Korea, many kids pick up StarCraft for the same reasons kids in America start playing football or baseball: respect from their peers and, just maybe, a chance at making it big in the pros. Jang Min Chul, 20, who goes by the player name MC, has nearly 30,000 Twitter followers. Park Soo Ho (a.k.a. DongRaeGu or DRG), also 20, was honored by the government of Busan, the city he grew up in, for his achievements in eSports.

But gamers in North America don’t grow up dreaming of sponsorships or adoring fans. Chris Loranger, 23, was about to join the military when a team recognized his talent. Now he spends half the year training in a house in South Korea and the other half competing as “HuK” in tournaments across the globe. While Loranger didn’t grow up surrounded by StarCraft hero worship, he’s definitely experiencing it now.

“If I stop to sign one autograph or take a picture or whatever (at an event), I will not move from that spot for maybe an hour and a half or two hours,” he says.